Lead Time: From Customer Ask to Customer Delivery
The customer’s clock, not yours
Lead time is the time from the customer's ask to the customer's delivery — the only clock the customer experiences. It does not matter that your machines are fast if the order waits four days for approval, six days in a queue, and three days on a dock. Customers do not feel your cycle times. They feel the total. Plants that manage by internal speed while ignoring lead time keep getting faster at steps the customer never sees, and keep losing orders to competitors who simply deliver sooner. Start every lead-time conversation with the customer's clock, or you are optimizing the wrong thing.
Where lead time hides
Lead time hides in the gaps, not in the work. Walk one order from ask to delivery and mark every wait: approval queues, batch accumulation, handoff delays, inspection backlogs, shipping schedules, and the inventory that sits "just in case" between every step. The work itself is usually a small fraction of the total; the waiting is the rest. That is good news disguised as bad news, because waiting is cheaper to remove than work is to speed up. You do not need faster machines to cut lead time in half. You usually need fewer queues, smaller batches, and handoffs that happen today instead of next week.
Little’s Law in plain English
There is a simple relationship governing the whole subject: lead time equals work in process divided by throughput. More work piled into the system, same rate of completion, longer wait for everything. It is why expediting makes things worse — rushing one hot job into an already full system slows everything else — and why limiting work in process is the fastest honest way to cut lead time. Pull systems work, at bottom, because they cap work in process. The math is not academic. It is the reason the plant with half the inventory delivers twice as fast, and the reason adding more starts without finishing more ends in a longer queue for everyone.
Shortening it without rushing people
Cutting lead time by rushing people is a short-term loan with a long-term price: defects, burnout, and a floor that stops telling the truth about problems. Honest lead-time reduction comes from flow and pull: smaller batches, fewer handoffs, leveled schedules, and signals instead of searches. Each removal of waiting shortens the customer's clock without asking anyone to run faster. Measure lead time weekly, post it where the team can see it, and treat growth in lead time as a problem with a cause — a new queue, a new approval, a batch that crept back — not as weather. The margin cost of waiting is laid out in The Silent Margin Drain, and the system is in The Lean Culture Blueprint. Track it daily from your pocket: https://apps.apple.com/us/app/lean-culture-advisory/id6790203662